Consumer tip-of-the-day: increasing efficiency of fuel economy on a miles-per-gallon scale is not linear, as more miles-per-gallon (mpg) are initially better for your wallet and the planet than you might expect, and eventually trail off with diminishing returns.

Fuel economy is not as straight-forward as you might think. Image courtesy: fragallo

If you are considering the fuel economy of a vehicle you are purchasing, remember the non-linearity of the metric when comparing options, as you might be comparing apples to oranges. Whether or not mpg is a good metric in the first place, I’ll leave to others to discuss.

An implication of improving conventional vehicle fuel economy is that electric vehicles and other alternative fuel vehicles will face a harder time competing with conventional vehicles as they increase in efficiency. Of course, as I have pointed out before, zero-emission vehicles are a long-term ambition, and at some point we need to switch away from conventional vehicles, so this does not make the overall effort void, rather it highlights the importance of interim market share gains.

So next time you’re in the market for a new car, remember that the differences in fuel economy might be deceiving. For example, 22 mpg versus 20 mpg is not equal to a 10% increase in efficiency; in fact, you might be saving more than you think. Now multiply that out by the US light-duty vehicle fleet of 96.6 million, and you’ll see why initial fuel economy improvements are essential to reducing energy use in the US.